Percutaneous implantable nuclear prosthesis

ABSTRACT

A prosthesis for implantation in a de-nucleated intervertebral disc includes a fiber ring-like layer which encloses a polymeric layer to create an annular space. The annular space is inflatable with an in-situ curable liquid polymer and forms an interior cavity. The annular space may be expanded uniformly or differentially to be tailored to the needs of a particular vertebral segment and to achieve optimal disc space width and angle, thereby stabilizing the segment while preserving normal motion of the vertebral segment. The interior cavity provides a void that allows inward deformation of the implant during weight bearing activities and bending. The prosthesis can be elastically deformed through axial elongation to a reduced profile to load into a delivery cannula using pulling techniques.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority of U.S. ProvisionalPatent Application No. 62/074,873, filed Nov. 4, 2014, which is herebyincorporated by reference in its entirety.

BACKGROUND

1. Field of the Invention

This application relates generally to methods and devices for repairingan intervertebral disc. More specifically, the application relates topercutaneously deployed implantable spinal discs and methods formanufacturing and deploying such discs.

2. Description of Related Art

A common medical issue is back pain due to spinal disc injuries causedby trauma, the aging process or other disorders. One method of treatmentthat has been proposed is to remove the existing nucleus pulposus andreplace it with a nuclear prosthesis (i.e., an artificial spinal disk)which is formed in situ using open surgery or minimally invasivesurgical techniques.

Prior artificial disc technology has generally employed two types ofimplants. One type is a total disc designed as a substitute for theentire disc including the nucleus pulposus, the annulus fibrosus, andthe vertebral end plates. The second type is a nuclear implant in whichthe annulus fibrosus and the end-plates are preserved. The shell formedby the annulus fibrosus itself has been used as an envelope to contain acurable biomaterial which is delivered to the cavity formed after anucleotomy. Alternatively, an additional membrane may be provided insidethe annulus fibrosus to form a shell to contain the biomaterial. Someprior art devices use two separate compartments or two nested balloons(a balloon placed within a balloon), which are filled in-situ withmaterials that have different hardnesses when cured, to simulate anatural disc.

In addition to artificial discs, a variety of systems have beendisclosed that immobilize the spinal segment, namely prostheses designedand intended for intervertebral disc fusion. The various systems includethe placement of cages, distendable sacks, fusion grafts, interbodyfusion rings, fiber bags and cushions and constraining jackets. Thesefusion devices employ different techniques than disc replacementsystems. Typically, these grafts are porous and they may be rigid ornon-rigid. Hardenable and load-bearing materials are introduced andconstrained by these structures to stabilize and fuse adjacentvertebrae.

Various techniques have been proposed for disc space distraction,including mechanical and hydrostatic techniques. For example, sometechniques utilize pressurized injection of a biomaterial insideinflatable balloons to separate adjacent vertebra.

The existing techniques for forming a nuclear prosthesis in situ havenot achieved convincing clinical acceptance or commercial success for avariety of reasons, including intricate designs that present problemspertaining to manufacture, implantation, and performance afterimplantation. Some of the problems associated with previous devices,specifically those related to percutaneous or minimally invasive designsintended for nuclear replacement, include:

-   1. Existing devices do not provide an integrated system that    provides access to the nucleus pulposus, a nuclear evacuation    apparatus that can achieve total or subtotal nucleotomy, and a    delivery apparatus for the nuclear implant.-   2. Existing devices inadequately seal the inflation device to the    balloon, which results in leakage of the injected material around    the inflation device during pressurized inflation.-   3. Existing devices use inadequate or unreliable valve systems for    preventing the curable biomaterial from leaking out of the implant    after inflation and prior to curing.-   4. Existing devices use hard materials that are insufficiently    deformable, elastic and/or compressible. For example, existing    devices often use a non-compressible center bearing portion to    resist migration or to provide a more flexible region that more    closely approximates the physical characteristics of the original    nucleus. However, the vertebral end-plates are weakest in the center    and strongest at the periphery. The use of a non-compressible center    bearing portion increases risk of subsidence in the center.    Furthermore, the lack of a central gas chamber or central void that    provides a space for inward deformation of the annular portion may    increase the risk of implant migration because of sudden or abnormal    increase in pressure during loading or twisting.-   5. Some existing devices attempt to construct an implant having a    rigid outer portion with a more liquid but non-compressible    interior. This design may work if the annulus is intact and can    provide adequate elasticity. In reality, most patients who are    candidates for disc replacement already have a damaged annulus, and    this type of device functions poorly with a damaged annulus.-   6. Existing devices provide inadequate nuclear evacuation, which    causes problems such as eccentric placement, less than optimal    peripheral placement with apposition of implant to inner annulus,    less than optimal weight distribution to the peripheral end-plates,    shifting of the implant and migration.-   7. Inadequate closure of the annulotomy defect due to required    surgical techniques. Existing techniques often involve cutting a    flap through the annulus.-   8. The materials used by existing devices are not durable and suffer    from failure after usage.-   9. Existing devices and techniques fail to restore and maintain    sufficient disc space height to keep the spinal support ligaments    taut.

Another issue with existing in situ formed prostheses is that it is verydifficult to precisely control the force required to withdraw theinflation and pressurization cannula from the implant. If this force istoo great, the implant may be dislodged through the annulotomy duringdetachment of the cannula. If the force required to withdraw the cannulafrom the implant is too small, the cannula may become prematurelydetached from the implant during pressurization. Furthermore, fluid mayleak around the connection.

The disclosed implant system is directed to overcoming one or more ofthe problems set forth above and/or other problems of the prior art.

SUMMARY

It is an object of the present application to provide a novelintervertebral disc for replacing a nucleus pulposus.

It is another object of the present application to provide a method offorming a nuclear prosthesis out of conformable materials which areadaptable to miniaturization.

It is yet another object of the present application to provide a methodof deforming a prosthesis to load it into a delivery cannula.

It is a further object of the present application to provide a method ofinserting and deploying a prosthesis into an intervertebral discutilizing minimally invasive surgery or percutaneously.

It is a still further object of the present application to provide avalve mechanism for preventing leakage of a curable material from animplanted prosthesis.

It is a yet further object of the present application to provide adevice which prevents subsidence and migration.

It is yet another object of the present application to provide a fluidconnector assembly which may provide a secure fluid seal duringpressurization of the implant within the disc, while still allowingefficient disengagement from the implant and not becoming prematurelydetached from the implant.

It is a yet further object of the present application to provide asimple, efficient, and repeatable manufacturing method.

Aspects of the present disclosure relate to an interbody spinalnon-fusion implant adapted for percutaneous deployment, and methods andinstruments for inserting and deploying such implants. In some exemplaryembodiments, a nuclear prosthesis is formed of a hollow ring-likesynthetic fiber graft which may be filled with a curable elastomer. Aone-way valve may be incorporated into the graft to allow elastomer tobe injected into the graft while preventing backflow. The valve may beleft in place to cure with the curable elastomer.

In some embodiment, the implant has a hollow ring-like configurationthat allows a generally circumferential increase in size. The expandableimplant may be designed to expand symmetrically or asymmetrically torestore disc height and angulation. Asymmetric expansion allow forchange in the degree of lordosis, lateral angulation, or degree ofcompliance, compressibility or elasticity of the implant according topatient needs. The implant parameters may be adjusted to tailorintervertebral axial spacing and angulation for a patient. For example,the expandability of the implant/graft walls may be altered, or thedurometer of the curable elastomer may be altered.

The ring-like implant forms an empty space in its interior. The interiorspace serves as a buffer zone for inward deformation of the curedelastomer within the lumen of the ring-like fiber graft.

The nuclear implant offers degrees of motion similar to those affordedby the anatomical spinal disc. Further, the durable biocompatiblematerials and design features provide a long working life. The nuclearimplant has similar weight bearing and hydraulic capabilities as thenucleus pulposus.

The cured elastomer within the fiber graft provides torsional andcompression stability. Thus, regardless of how loads are applied, thevectors of forces are substantially redirected centrally toward theinterior cavity. Further, the fabric graft limits outward movement inthe radial direction to lower stress on the annulus fibrosus.

Inflation of the implant separates the vertebral bodies along thecranial-caudal axis. This stretches and tightens the fibers of theannulus fibrosus to stabilization the spinal motion segment. Bystabilizing the vertebral segment, while avoiding fusion, the repetitivetraumatic forces on the ligaments and facet joints are reduced, thusslowing down the degenerative process and the development of spinalstenosis. Furthermore, by avoiding spinal fusion, the graft curtails thepossibility of development of adjacent segment disease.

An aspect of the present disclosure is to preserve normal motion andreverse or arrest the degenerative cascade leading to segmentalinstability. This will alleviate pain and preserve the structuralstability of the annulus fibrosus, facet joints and other osseousstructures and ligaments.

Embodiments of the present disclosure include an artificial nuclearimplant comprising an annular fiber graft which is inflated with anin-situ curable elastomer to form an interior cavity that allows inwarddeformation of the elastomer.

In one exemplary embodiment, the annular implant occupies the peripheralaspect of an evacuated disc space and is opposed to the inner margin ofthe annulus fibrosus and to the end-plates of the adjacent upper andlower vertebral bodies. A fluid is delivered into a lumen of the annularimplant to create pressure to expand the implant and distract theadjacent vertebrae. After the access, delivery and inflation devices areremoved, the elastomeric material cures in-situ within the annular graftto maintain vertebral distraction. The implant shares weight bearing andstabilization functions with the intrinsic annulus, which has beenweakened by degeneration, fissures, or tears. A goal of the implant isto restore normal anatomical intervertebral spacing and angle andstabilization of the vertebral segment, while preserving its normalrange of biomechanical movement.

In one aspect of the present disclosure, an implantable prostheticdevice comprises an annular tubular inflatable membrane having aninflation port; a tubular fiber graft enclosing the inflatable membrane;an inflation stem coupled to the inflation port for removably receivingan inflation stylet in a substantially leakproof manner; and a one wayvalve assembly in the inflation stem to allow fluid to be injected intothe interior of the inflatable membrane, the one way valve assemblycomprising a flutter-type or duckbill valve.

In another aspect of the present disclosure, an implantable prostheticdevice comprises an annular tubular inflatable membrane having aninflation port and first and second open ends; a tubular fiber graftenclosing the inflatable membrane and having first and second open ends;a coupling member coupling the first and second open ends of theinflatable membrane and fiber graft; and a one way valve assemblycoupled to the inflation port to allow fluid to be injected into theinterior of the inflatable membrane, the one way valve assemblycomprising a flutter-type or duckbill valve.

In a further aspect of the present disclosure, a kit for implanting animplantable prosthetic device comprises a delivery cannula having aninternal lumen with an inner diameter; a graft comprising an annularinflatable ring with an inflation stem for communicating with aninterior of the annular inflatable ring, wherein the inflation stem hasa proximal end and an opposed distal end and has an outer diameter andan inner diameter, and wherein the inflation stem is disposed in theinternal lumen of the delivery cannula; a release cannula slidablydisposed in the delivery cannula, the release cannula having a distalportion configured to engage the proximal portion of the inflation port,and an inflation stylet with at least one internal lumen, the inflationstylet having a distal portion with an outer diameter configured to bereleasably press fit into the inflation stem.

In yet another aspect of the present disclosure, a method ofmanufacturing an implant comprises forming a tubular elastomericmembrane with first and second open ends and an inflation port;enclosing the elastomeric membrane in a tubular fiber graft; andcoupling the first and second open ends together.

In an additional aspect of the present disclosure, a method of forming agraft comprises providing an implant as described herein; deploying theimplant into a disc cavity; inflating the implant with a curablematerial; and allowing the curable material to cure.

The term “coupled” is defined as connected, although not necessarilydirectly. The terms “a” and “an” are defined as one or more unless thisdisclosure explicitly requires otherwise. The terms “substantially,”“approximately,” and “about” are defined as largely but not necessarilywholly what is specified (and includes what is specified; e.g.,substantially 90 degrees includes 90 degrees and substantially parallelincludes parallel), as understood by a person of ordinary skill in theart. In any disclosed embodiment, the terms “substantially,”“approximately,” and “about” may be substituted with “within [apercentage] of” what is specified, where the percentage includes 0.1, 1,5, and 10 percent.

The terms “comprise” (and any form of comprise, such as “comprises” and“comprising”), “have” (and any form of have, such as “has” and“having”), “include” (and any form of include, such as “includes” and“including”) and “contain” (and any form of contain, such as “contains”and “containing”) are open-ended linking verbs. As a result, a system,or a component of a system, that “comprises,” “has,” “includes” or“contains” one or more elements or features possesses those one or moreelements or features, but is not limited to possessing only thoseelements or features. Likewise, a method that “comprises,” “has,”“includes” or “contains” one or more steps possesses those one or moresteps, but is not limited to possessing only those one or more steps.Additionally, terms such as “first” and “second” are used only todifferentiate structures or features, and not to limit the differentstructures or features to a particular order.

A device, system, or component of either that is configured in a certainway is configured in at least that way, but it can also be configured inother ways than those specifically described.

Any embodiment of any of the systems and methods can consist of orconsist essentially of—rather than comprise/include/contain/have—any ofthe described elements, features, and/or steps. Thus, in any of theclaims, the term “consisting of” or “consisting essentially of” can besubstituted for any of the open-ended linking verbs recited above, inorder to change the scope of a given claim from what it would otherwisebe using the open-ended linking verb.

The feature or features of one embodiment may be applied to otherembodiments, even though not described or illustrated, unless expresslyprohibited by this disclosure or the nature of the embodiments.

Details associated with the embodiments described above and others arepresented below.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional view of an implant according to an embodiment ofthe present disclosure after implantation into an intervertebral space;

FIG. 2 is a sectional view of the inflation port and valve assembly ofthe implant of FIG. 1;

FIG. 3 is a sectional view taken along line 3-3 in FIG. 2;

FIG. 4 is a plan view of an inflatable membrane of the implant of FIG.1;

FIG. 5 is a plan view of a mandrel for making the inflatable membrane ofthe implant of FIG. 1;

FIG. 6 is a plan view of a tubular fiber graft of the implant of FIG. 1;

FIG. 7 is a plan view of an access opening in the tubular fiber graft ofFIG. 6;

FIG. 8 is a partial sectional view of a portion of the implant of FIG.1, prior to installation of a retaining member;

FIG. 9 is a partial sectional view of a portion of the implant of FIG.1, after installation of a retaining member;

FIG. 10 is a sectional view of a delivery cannula with the implant ofFIG. 1, prior to deployment;

FIG. 11 is a sectional view of an alternative embodiment of an inflationstylet;

FIG. 12 is a sectional view of the implant of FIG. 1 which is partiallyimplanted into the intervertebral space;

FIG. 13 is a sectional view of the implant of FIG. 1 which is partiallyimplanted into the intervertebral space with a push member;

FIG. 14 is a diagrammatic view of an implanted implant of FIG. 1 withthe adjacent vertebrae substantially aligned;

FIG. 15 is a diagrammatic view of an implanted implant of FIG. 1 withthe adjacent vertebrae bent towards one another; and

FIG. 16 is a diagrammatic view of an implanted implant of FIG. 1 withthe adjacent vertebrae bent towards one another.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, in which are shown exemplary but non-limiting andnon-exhaustive embodiments of the invention. These embodiments aredescribed in sufficient detail to enable those having skill in the artto practice the invention, and it is understood that other embodimentsmay be used, and other changes may be made, without departing from thespirit or scope of the invention. The following detailed description is,therefore, not to be taken in a limiting sense, and the scope of theinvention is defined only by the appended claims. In the accompanyingdrawings, like reference numerals refer to like parts throughout thevarious figures unless otherwise specified.

FIG. 1 illustrates an implant 100 in accordance with an exemplaryembodiment of the present disclosure after deployment into a disc cavity102. The disc cavity 102 is formed by performing a discectomy to removethe natural spinal disc. In some embodiments, the discectomy isperformed using minimally invasive techniques, such as percutaneoustechniques, so that the annulus fibrosus 104 is left substantiallyintact, with only a small access opening.

The implant 100 comprises an annular ring 106 which is filled with acurable elastomeric material 108, such as a curable silicone elastomer.The properties of material 108 may be selected to provide desiredproperties for the implant 100. For example, curing time, cureddurometer, and other physical properties, such as elongation, tear, andtensile strength may be selected to provide implant 100 with desiredcharacteristics.

Implant 100 forms a interior cavity 110 in the interior of annular ring106. Interior cavity 110 allows annular ring 106 to deform inwardly torelieve stress and avoid placing excessive pressure on the centralregion of the vertebral end plates, as will be described in furtherdetail below.

Annular ring 106 has an inflation port 114 with a one-way valve assembly116 which allows curable material 108 to be introduced into annular ring106 while it is still in a flowable state (i.e., prior to curing) whilepreventing curable material 108 from leaking out. In certainembodiments, annular ring 106 is formed by a tubular inflatable membrane134 and a tubular fiber graft 136 which encloses the inflatable membrane134.

Referring to FIG. 2, inflatable membrane 134 forms an annular balloon138 with inflation port 114. A one-way valve assembly 140 is coupled tothe inflation port 114. One-way valve assembly 140 allows curablematerial to be injected into annular balloon 138 while preventingsubstantially any material from escaping. In some embodiments, inflationport 114 comprises an inflation neck 208 which is formed integrally withinflatable membrane 134. In certain embodiments, an inflation stem 142with a lumen 148 extending from a proximal end 144 to a distal end 146is inserted into inflation neck 208 and coupled to inflation neck 208 byadhesive, welding, or the like. One way valve assembly 140 may comprisea duckbill valve (i.e., a flutter-type or Heimlich valve) 150 comprisinga thin elastomeric material extending from inflation stem 142. The thinelastomeric material of duckbill valve 150 stretches to allow curablematerial 108 to flow through it when pressure is applied to curablematerial 108. When pressure is removed, the thin elastomeric materialconstricts to prevent back-flow. Duckbill valve 150 may be coupled toinflation stem 142 prior to assembly with inflatable membrane 134, ormay be coupled to inflation stem 142 after inflation stem 142 is coupledto inflatable membrane 134. One-way valve assembly 140 and inflationstem 142 may be placed substantially in the inflation neck 208. That is,they may be placed so that they are outside of the annular portion ofinflation membrane 134. Placing the inflation and valve componentryoutside of the annular portion of inflation membrane 134 easesmanufacturing, improves the function of implant 100 during deployment,and improves the functionality and durability of implant 100 afterdeployment.

In some embodiments, inflatable membrane 134 is formed of an elasticmaterial, such as silicone, so that it is compliant (i.e., it expands asthe internal pressure increases). A compliant balloon reduces the needfor precise sizing of the membrane. In other embodiments, inflatablemembrane 134 is semi-compliant. That is, inflatable membrane 134 expandsto a given diameter under a certain amount of pressure, and only expandsmoderately from this diameter as the internal pressure increases beyondthat pressure. Semi-compliant inflatable membranes 134 may beadvantageous in some circumstances.

Inflatable membrane 134 may be formed by conventional techniques, suchas extrusion, injection molding or dip casting. In some embodiments,inflatable membrane 134 is formed by injection molding. Referring toFIGS. 4 and 5, a core mandrel 152 is used in conjunction withcorresponding injection molding dies (not shown). In some embodiments,mandrel 152 comprises three pieces 154, 156, 158 which may be removablyattached to one another by interlocking joints, such as threads or keys.Mandrel 152 is placed into the molding dies, and uncured silicone isinjected into the die and allowed to cure to form inflatable membrane134. After inflatable membrane 134 is cured, the molding dies areopened, and the mandrel with the inflatable membrane 134 is removed. Themandrel may then be removed through inflation port 114 and inflationneck 208. In some embodiments, mandrel pieces 154, 156 and 158 aredisassembled and removed through inflation port 114 and inflation neck208. In other embodiments, inflatable membrane 134 may be cut to formfirst and second legs 160, 162 with open ends 120, 122 through whichmandrel pieces 156 and 158 are removed. In certain embodiments, firstand second legs 160, 162 of inflatable membrane 134 are approximatelythe same length, although they may be unequal lengths.

Cutting inflatable membrane 134 to form legs 160, 162 allows tubularfiber graft 136 to be formed separately and then installed on inflatablemembrane 134. Referring to FIGS. 6 and 7, in some embodiments, tubularfiber graft 136 comprises a textile formed of a biocompatible material.The textile material may be a woven, braided or knitted durablebiocompatible material. In some embodiments, tubular graft 136 comprisesa first layer comprising a plurality of semi-elastic or substantiallyinelastic fibers extending longitudinally and circumferentially alonggraft 136. In certain embodiments, a second layer of semi-compliantfibers are layered over the first layer. In other embodiments,circumferential fibers are formed from substantially inelasticmaterials, and hoop fibers are formed from semi-elastic materials. Thisallows the graft 100 to expand moderately in the cross-sectional planewhile constraining radial or equatorial expansion. In this manner, graft100 mostly deforms inward toward interior cavity 110 and in the axial orcraniocaudal plane. In some embodiments, tubular fiber graft 136incorporates radiopaque markers at one or more locations to enableclinicians to visualize graft 100 during implantation. In certainembodiments, the radiopaque markers comprise radiopaque fibers.

The cross-sectional diameter of tubular fiber graft 136 is selected toallow inflatable membrane 134 to be inflated to full size whilepreventing over-expansion of inflatable membrane 134. The materials areselected so that inflatable membrane 134 does not bond to fiber graft136 and is free to move within fiber graft 136 to a limited extent.

In some embodiments, tubular fiber graft 136 is a split annular ringwith first and second open ends 164, 166. An opening 168 is provided intubular fiber graft 136 to provide access to inflation port 114. Opening168 may be reinforced by stitching (e.g., a buttonhole stitch). Further,a reinforcing member 170 may be provided to reinforce the opening. Fibergraft 136 is installed over inflatable member 134 by placing inflatablemember 134 through either first and second open end 164, 166 andthreading it through fiber graft 136. Inflation neck 208 is placedthrough opening 168.

Open ends 164, 166 of fiber graft 136 and open ends 120, 122 ofinflatable membrane 134 are coupled to one another to form implantannular ring 106. In one embodiment, a coupling member 124 is providedto couple open ends 164, 166 and open ends 120, 122. Referring to FIGS.8 and 9, coupling member 124 comprises a cylindrical member with agroove 172. In FIGS. 8 and 9, inflatable member 134 and fiber graft 136form first and second tubular legs 174, 176 with open distal ends 178,180, respectively. For clarity, inflatable membrane 134 and fiber graft136 are shown as a single line in FIGS. 8 and 9. Coupling member 124 isplaced into the interior of open distal end 180 of second tubular leg176, and open distal end 178 of first tubular leg 174 is placed overcoupling member 124 and distal end 180 of second tubular leg 176. Aretaining member 182 is placed over coupling member 124 to couple distalends 178, 180 to coupling member 124. In some embodiments, retainingmember 182 is a permanently crimpable member which is crimped intogroove 172. Retaining member 182 may comprise a radiopaque material toserve as a radiopaque marker.

In some embodiments, coupling member 124 may be a solid member whichforms a partition to prevent fluid communication between first andsecond tubular legs 174, 176. In other embodiments, coupling member mayhave a lumen which connects first and second tubular legs 174, 176.

FIG. 10 illustrates implant 100 loaded into percutaneous deploymentdevice 112. Percutaneous deployment device 112 comprises a deliverycannula 128, a release cannula 130 and an inflation stylet 132.Deployment device 112 may be placed in an introducer or access cannula126. Access cannula 126 extends through annulus fibrosus 104 to provideaccess to disc cavity 102. Access cannula 126 is deployed usingconventional percutaneous access techniques. Access cannula 126 may be aconventional cannula. In some embodiments, access cannula 126 comprisesan access cannula used to remove the nucleus pulposus, such as theaccess cannula described in US Patent Publication No. 2014/0276832,entitled “Surgical Device,” which is hereby incorporated by reference inits entirety. Implant 100 is stretched out in a deflated state andplaced into delivery cannula 128. The inner diameter of delivery cannula128 is substantially the same as the outer diameter of inflation stem142 so that inflation stem 142 fits snugly into delivery cannula 128.The outer diameter of release cannula 130 is selected to fit snugly intodelivery cannula 128. The distal end 184 of release cannula 130 engagesthe proximal end 144 of inflation stem 142 so that release cannula 130can be used to push inflation stem 142 and thus implant 100 out of theend of delivery cannula 128 to deploy implant 100 into disc cavity 106.Release cannula 130 can also be used to hold inflation stem 142 intoplace while withdrawing inflation stylet 132 after deployment (as willbe described in further detail below).

Inflation stylet 132 is placed into inflation stem 142. Inflation stem142 is elastic and stretched to fit over the outer diameter of inflationstyle 132 so that the two pieces fit together snugly. The snug fit ofinflation stylet 132 into inflation stem 142 together with the snug fitof inflation stem 142 into delivery cannula 128 form a tight seal tosubstantially prevent leakage during deployment and inflation of implant100. Furthermore, the snug fit prevents inadvertent dislodgment of theinflation stylet prior before completion of the inflation, despite therelatively high pressures which may be used to inflate inflatablemembrane 134.

Referring to FIG. 11, in certain embodiments, inflation stem 186 istapered from a proximal end 194 to a distal end 196. A distal end 198 ofthe inflation stylet 198 forms a complementary shape. A lock 200releasably holds inflation stylet 198 in inflation stem 186. In certainembodiments, lock 200 comprises a protuberance 192 which engages agroove 190. In certain embodiments, protuberance 192 comprises a ridgemolded around inflation stylet 198. The size, shape and number of ridgesand grooves can be selected to provide a desired force required todetach the inflation stylet from the inflation stem.

Referring to FIG. 12, to deploy implant 100, the existing nucleuspulposus at the target site is removed by inserting access cannula 126through a small access opening through the annulus fibrosus 104. Theexisting nucleus pulposus is removed through access cannula 126 byperforming a discectomy. The annulus fibrosus 104 is left substantiallyintact to form disc cavity 102.

Implant 100, which has been loaded into percutaneous deployment device112, is inserted into the disc space. Release cannula 130 and inflationstylet 132 are pressed toward disc cavity 102 to engage proximal end 144of inflation stem 142 and begin to deploy implant 100. In certainembodiments, a push member 210 extends from inflation stylet 132 andengages coupling member 124. During deployment, push member 210 pushescoupling member 124 toward the far end of the disc cavity 102 to helpensure proper placement of implant 100.

Alternatively, release cannula 130 may be advanced so that implant 100is partially deployed, and curable material 108 may be delivered throughinflation stylet 132 to partially inflate inflatable membrane 134.Release cannula 130 may then be advanced again, and additional curablematerial 108 may be delivered. This process is repeated until inflationstem 142 has been advanced to the distal end of delivery cannula 128,thereby fully deploying implant 100.

After implant 100 is fully deployed into disc cavity 102, curable 108 isdeployed into the inflatable membrane 134 to press implant 100 firmlyagainst annulus fibrosus 104 and distract adjacent vertebral segments. Apressurized syringe may be used to deploy curable material 108 andsupply sufficient pressure achieve the desired intervertebraldistraction. After sufficient curable material 108 is deployed,inflation stylet 132 may be removed. Release cannula 130 holds inflationstem 142 into place, thereby preventing inadvertent withdrawal ofimplant 100 when inflation style 132 is removed. One-way valve 116prevents curable material 108 from leaking out of implant 100. Thus,inflation stylet 132 may be removed prior to curing of curable material108. When inflation stylet 132 is removed, inflation stem 142, which isformed of an elastomeric material, collapses so that it only leaves asmall amount of material in the opening of the annulus fibrosus (i.e.,the annulotomy). The collapsed inflation stem 142 reinforces thefunction of duckbill valve 150 by preventing duckbill valve 150 frominverting due to the pressure of the curable material (prior to curing).

Curable material 108 may be a silicone elastomer. The properties of thematerial, such as the curing time, uncured viscosity, cured durometer,etc. may be selected as desired to provide the desired properties forgraft 100, which are dependent upon the patient under treatment. Thecurable material 108 may be compatible with the material of inflatablemembrane 134 so that they fuse together and form a single component.

Referring to FIGS. 13-15, once implant 100 has cured, it forms asubstantially non-compressible ring 106 which is contained withinannulus fibrosus 104. Implant 100 distracts adjacent vertebral segments202 by pressing against vertebral end plates 204. Interior cavity 110 isformed in the center of annular ring 106. When vertebral segments 202are moved with respect to one another, annular ring 106 deforms intointerior cavity 110. This prevents implant 100 from being subjected totoo high of pressures, and prevents implant 100 from applying too highof pressures to vertebral end plates 204. Furthermore, the peripherallocation of implant 100 distributes weight to the peripheral portions ofthe vertebral end plates, and interior cavity 110 prevents excessiveforce from being applied to the central region 206 of vertebral endplates 204. The peripheral portions of the end plate are typicallystronger than the central regions. Further, interior cavity 110 providesspace for shock absorption and for inward deformation during loading andsudden increases in intradiscal pressure.

The above specification and examples provide a complete description ofthe structure and use of exemplary embodiments. Although certainembodiments have been described above with a certain degree ofparticularity, or with reference to one or more individual embodiments,those skilled in the art could make numerous alterations to thedisclosed embodiments without departing from the scope of thisinvention. As such, the various illustrative embodiments of the presentdevices are not intended to be limited to the particular formsdisclosed. Rather, they include all modifications and alternativesfalling within the scope of the claims, and embodiments other than theone shown may include some or all of the features of the depictedembodiment. For example, components may be combined as a unitarystructure, and/or connections may be substituted (e.g., threads may besubstituted with press-fittings or welds). Further, where appropriate,aspects of any of the examples described above may be combined withaspects of any of the other examples described to form further exampleshaving comparable or different properties and addressing the same ordifferent problems. Similarly, it will be understood that the benefitsand advantages described above may relate to one embodiment or mayrelate to several embodiments.

The claims are not intended to include, and should not be interpreted toinclude, means-plus- or step-plus-function limitations, unless such alimitation is explicitly recited in a given claim using the phrase(s)“means for” or “step for,” respectively.

The invention claimed is:
 1. An implantable prosthetic devicecomprising: a) an annular hollow inflatable membrane having an inflationport, wherein the annular hollow inflatable membrane comprises aunitary, elastomeric member with a first open end and a second open endwhich are coupled together by a coupling member; b) a tubular fibergraft enclosing the inflatable membrane; c) a retaining member forcoupling the annular hollow inflatable membrane and the tubular fibergraft to the coupling member; d) an inflation stem coupled to theinflation port for removably receiving an inflation stylet in asubstantially leakproof manner; and e) a one way valve assembly in theinflation stem to allow fluid to be injected into an interior of theinflatable membrane, the one way valve assembly comprising a duckbillvalve.
 2. The implantable prosthetic device of claim 1, wherein thecoupling member further comprises a lumen for fluidly connecting thefirst and second open ends of the annular hollow inflatable membrane. 3.The implantable prosthetic device of claim 1, wherein the inflation portfurther comprises an inflation neck extending from the annular hollowinflatable membrane.
 4. The implantable prosthetic device of claim 3,wherein the inflation stem comprises a single lumen.
 5. The implantableprosthetic device of claim 3, wherein the tubular fiber graft comprisesan opening for receiving the inflation neck of the annular hollowinflatable membrane.
 6. The implantable prosthetic device of claim 1,further comprising a deployment device comprising: a delivery cannulafor receiving the inflatable membrane and tubular fiber graft in anuninflated state; a pushrod for moving the coupling member away from theinflation stem a towards a distal end of a disc cavity; an inflationstylet for delivering a curable material to the inflatable membrane; anda release cannula for allowing the inflation stylet to be removedwithout dislodging the inflatable membrane.
 7. The implantableprosthetic device of claim 6, wherein the inner diameter of the deliverycannula and the outer diameter of the inflation stem are substantiallythe same, and wherein the graft comprises an annular inflatable graftthat defines a hollow cavity when inflated.
 8. The implantableprosthetic device of claim 1, wherein the coupling member comprises alumen connecting the first and second open ends of the annular hollowinflatable membrane, and wherein the coupling member is opposite theinflation port when the annular hollow inflatable membrane is inflated.9. An implantable prosthetic device comprising: a) an annular inflatablemembrane having an inflation port and first and second open ends, theannular inflatable membrane comprising a unitary, elastomeric member; b)a tubular fiber graft enclosing the inflatable membrane and having firstand second open ends; c) a coupling member coupling the first and secondopen ends of the inflatable membrane and fiber graft, wherein thecoupling member comprises a lumen connecting the first and second openends of the annular inflatable membrane, and wherein the coupling memberis opposite the inflation port when the annular inflatable membrane isinflated; and d) a one way valve assembly coupled to the inflation portto allow fluid to be injected into an interior of the inflatablemembrane, the one way valve assembly comprising a duckbill valve. 10.The implantable prosthetic device of claim 9, further comprising aretaining member for coupling the annular inflatable membrane and thetubular fiber graft to the coupling member.
 11. The implantableprosthetic device of claim 9, further comprising an inflation stemdetachably coupled to the inflation port for receiving an inflationstylet, wherein the coupling is substantially leakproof duringinflation.
 12. The implantable prosthetic device of claim 11, furthercomprising a locking device on the inflation stem configured to engage amating locking device on the inflation stylet to prevent inadvertentdislodgement of the inflation stylet.
 13. The implantable prostheticdevice of claim 11, wherein the inflation stem is located outside of achamber formed by the annular inflatable membrane.
 14. The implantableprosthetic device of claim 11, wherein the inflation stem comprises asingle lumen, and wherein the duckbill valve comprises a flutter valve.15. The implantable prosthetic device of claim 11, further comprising aninflation stylet adapted to mate with the inflation stem.
 16. Theimplantable prosthetic device of claim 9, wherein the inflatablemembrane comprises an inflation neck extending from the inflation port.17. The implantable prosthetic device of claim 16, wherein the tubularfiber graft comprises an opening for receiving the inflation neck of theinflatable membrane.
 18. The implantable prosthetic device of claim 9,further comprising a deployment device comprising: a delivery cannulafor receiving the inflatable membrane and tubular fiber graft in anuninflated state; an inflation stylet for delivering a curable materialto the inflatable membrane; and a release cannula for allowing theinflation stylet to be removed without dislodging the inflatablemembrane.
 19. The implantable prosthetic device of claim 18, furthercomprising an inflation stem coupled to the inflation port wherein theinflation stem is configured to receive the inflation stylet andconfigured to be placed into the delivery cannula.
 20. A kit forimplanting an implantable prosthetic device, comprising: a) a deliverycannula having an internal lumen with an inner diameter; b) a graftcomprising an annular inflatable ring with an inflation stem forcommunicating with an interior of the annular inflatable ring, wherein:the inflation stem has a proximal end and an opposed distal end and hasan outer diameter and an inner diameter, and wherein the inflation stemis disposed in the internal lumen of the delivery cannula and includes aduckbill valve; and the inner diameter of the delivery cannula and theouter diameter of the inflation stem are substantially the same, andwherein the graft comprises an annular inflatable graft that defines ahollow cavity when inflated; c) a release cannula slidably disposed inthe delivery cannula, the release cannula having a distal portionconfigured to engage a proximal portion of the inflation stem; and d) aninflation stylet with at least one internal lumen, the inflation stylethaving a distal portion with an outer diameter configured to bereleasably press fit into the inflation stem.